1. Field of the Invention
The present invention generally relates to a wafer sawing apparatus, and more particularly to a wafer sawing apparatus which can remove substantially all of the silicon particles as well as dissipate any heat which is generated by the friction between the wafer and the scribing blade during the wafer sawing process.
2. Background of the Related Art
In semiconductor device fabrication, a wafer sawing process is performed to divide a silicon wafer on which a plurality of integrated circuits (ICs) are formed into separate individual semiconductor chips by using a wafer sawing apparatus having a diamond-pointed scribing blade.
FIG. 1 is a perspective view depicting a conventional wafer sawing apparatus. In FIG. 1, a wafer sawing apparatus 100 is used in wafer scribing equipment, for example, model DFD-640 which is manufactured by DISCO (Japan). Referring to FIG. 1, the wafer sawing apparatus 100 has a scribing blade 70 combined with an output shaft 64 of a spindle motor 62, the output shaft 64 and the scribing blade 70 being rotated by the force of the spindle motor 62. Two side nozzles 72 for ejecting a washing solution 90 are positioned on each side of the scribing blade 70 and are connected to a body 66 of the wafer sawing apparatus 100. Each side nozzle 72 comprises a plurality of separate sub-nozzles 76. A center nozzle 74 also for ejecting the washing solution 90 is positioned adjacent to and aligned with the cutting edge of the scribing blade 70, is located ahead of the cutting edge in the driving direction, and is also connected to the body 66 of the wafer sawing apparatus 100.
By using the wafer sawing apparatus 100, the wafer sawing process is performed as follows to divide a silicon wafer on which a plurality of integrated circuits (ICs) are formed into a plurality of separate individual semiconductor chips. After loading the wafer 50 which has a plurality of the ICs 52 onto a table 42, the scribing blade 70 which is combined with the output shaft 64 of the body 66 is rotated by the spindle motor 62 of the wafer sawing apparatus 100, and scribes the wafer 50 along scribe lines or scribe streets 54. Then, the wafer 50 is divided into a plurality of separate individual ICs 52.
As the above-stated scribing blade 70 scribes the wafer 50, it abrades the silicon away, producing small silicon particles or debris. The silicon particles which remain on the top surface of the wafer after the wafer sawing process has been completed cause many failures in subsequent manufacturing processes, for example failures in the wire-bonding or the molding processes. Further, the heat which is generated by the friction between the wafer 50 and the scribing blade 70 may damage the ICs 52 on the wafer 50. Therefore, the wafer sawing apparatus 100 utilizes the side nozzles 72, which spray the washing solution 90 onto the top surface of the wafer 50, and the center nozzle 74, which sprays the washing solution 90 onto the scribing blade 70, during or after the wafer sawing process, in order to flush away the silicon particles and to dissipate the heat. The washing solution 90 which is ejected through the side nozzles 72 and the center nozzle 74 attempts to cool the heated scribing blade 70 and the heated wafer 50. Further, the washing solution 90 attempts to clean the top surface of the wafer 50 and reduce the friction between the scribing blade 70 and the wafer 50. In general, DI water (deionized water) is used as the washing solution 90.
However, the wafer sawing method using the above-described wafer sawing apparatus 100 cannot throughly flush away all the silicon particles, and some abraded silicon particles remain on the top surface of the wafer. Also, fine particles of silicon float in the air and settle onto the top surface of the wafer. Consequently, these abraded and fine particles of silicon disturb the subsequent manufacturing processes.
Such contamination is of even greater concern when manufacturing charge coupled devices (CCDs), which are assembled under a class 10 or less cleanliness condition. The fine particles of silicon and inductive dust which settle onto the top surface of the device on the wafer cause failures by adversely affecting the monitor or screen of a product incorporating the CCDs. The term `class` means a cleanliness condition having the indicated number of particles with a diameter of 0.5 .mu.m or more per 1 ft.sup.3. For example, devices other than the CCDs are generally assembled under cleanliness conditions of approximately class 1000.
Therefore, the silicon particles remaining on the top surface of the wafer reduce the yield and productivity, and further deteriorate the performance of the products which are made from the wafer.